Some time ago I had a little portrait session with my guitar teacher Karl Allaut.He's one of the founding members of Udo Linderbergs Panik Orchester,and today totally dedicated to Jazz music with his Archtop guitar.This is one of the images I don't find totally bad, so I dare to post it here.For the interested: Mamiya Universal, Sekor 100 mm F2.8, T-Max 100, scanned with a Nikon LS 9000

On purely compositional grounds, I find the environment too distracting, with all those couch patterns. Case for a lot of edge vignetting or background darkening?

This also seems to be the case where a slight tilt of the camera might have resulted in a more dynamic composition, e.g., guitar running more diagonally, rather than the static position of being almost parallel to the edge of the image and edge of the couch.

Yes and Yes.The Clarity served as a sort of sharpness here - I wanted the contrast between the sharp and unsharp areas to be more pronounced.The portrait was intentionally done in the "natural habitat" of him, but I see the sofa as problematic myself.Since it was a first session and a sort of experiment for me - my first portrait session with that camera, I didn't want to have to control too many parameters at the beginning and decided not to arrange or control much here.For me this type of portraying is huge challenge and a steep learning curve, especially the lighting (I used 2 strobes, one with a softbox).

Aha! Strobe lighting... Here is how I would have solved the busy background problem: I would have positioned one strobe slightly behind him, and thus throw the background into a shadow, with another strobe (with the softbox) very close to his face, which would provide for a fill-in and throw the background into darkness. The purpose of bringing it close to the face is to utilize the property of light to fall sharply with the distance squared (i.e., objects twice distant from the main one would receive a quarter of light intensity). Hope this helps.

Christoph, Slobodan's been direct but uncharacteristically polite and I'm not sure the message is getting through. The fact is that the kind of lighting you're using in this picture is appropriate when you're photographing a wrench or a pair of pliers. It doesn't work too well with a person. To see the correct use of this lighting check Walker Evans's tool pictures. They're exceptional. Since your guitar teacher isn't a tool, you might want to try a different approach.

Seems to be my biggest mistake when doing portraits - too harsh and direct light all the time - I'll get some styro foam for reflectors.I think this is the field where I can learn the most in the moment.